1. Field of the Invention
The present invention relates to an exhaust silencer for internal combustion engines, in particular, 2-stroke cycle engines of, for example, a powered portable sprayers for spraying chemicals over, for example, a rice field or portable lawn mowers used in trimming lawn in a park or the like and, more particularly, to an exhaust silencer which is improved to prevent deposition of tar component of exhaust from the engine on sound absorbing material in the exhaust silencer.
2. Description of the Related Art
In general, exhaust gases from a compact 2-stroke cycle internal combustion engine are released into the atmosphere via an exhaust silencer which reduces the exhaust noise. In order to enhance the noise reduction, a sheet of sound absorbing material such as a felt-like material made of glass wool is laid on the inner surface of the exhaust silencer and retained in place by means of a rigid wire gauze overlaying the surface of the sound absorbing material.
Thus, in the conventional exhaust silencer, the sound absorbing material is directly exposed to the exhaust gases through the meshes of the rigid wire gauze.
Exhaust from a compact 2-stroke cycle engine contains unburnt components of lubricating oil which deposits on and permeates into the sound absorbing material in the form of a tar, resulting in significant reduction in the silencing effect of the sound absorbing material, as well as other detriments such as increase in the weight of the exhaust silencer and an damage to the same.